Diagnostics Archives - UnderhoodService
Diagnosing Misfires

What if there are no codes and a misfire is intermittent? This is where it gets complicated.

Using a Scope

Ignition coil and plug diagnostics.

Scope-diagnostics
Repairing Wiring Harnesses

A guide to probing and poking.

Lifter Deactivation

The area of contact between the lifters and cam lobes is the highest loaded surface inside an engine.

Diagnostic Procedures For Stop/Start Systems

Stop/start technology is more than just a switch wired to the brake pedal and starter.

Alternator Testing For No Charge Conditions

Many alternator problems turn out to be nothing more than a bad connection at the alternator or a bad wiring harness.

Diesel Air Filter Replacement

Here are some diesel air filter replacement tips in order to keep these vehicles running as intended.

Auxiliary Cooling Pumps

An auxiliary cooling pump’s primary function is to circulate warm coolant to the heater core.

Battery Management Means Knowing How It Ages

The battery may be fully charged, but you also need to measure how low the voltages go while the engine is cranking.

Deciphering Engine Misfire Codes

When the fuel/air mixture ignites, many factors must be met to pass a misfire monitor.

Ignition System Do’s and Don’ts

Why do ignition systems give technicians problems when diagnosing ignition-related misfires? The answer is that some technicians use tests that might give inconclusive results or do damage to the coil or drivers inside a module.

Charging for Diagnostic Time

Diagnostic work is more sophisticated and your techs’ time is worth charging for. This video is sponsored by Auto Value and Bumper to Bumper.